Dock seals and shelter are typically employed at loading docks for the purpose of forming a seal or at least a barrier to the elements between the back of a vehicle parked at the loading dock for loading and unloading purposes, and the building or warehouse within. A traditional dock shelter, such as the WG402 unit sold by Frommelt Products Corporation of Dubuque, IA, employs a rigid frame structure mounted to the building wall adjacent the loading dock. Coupled to this rigid structure, are a pair of side curtains which extend inward from the frame structure toward the vehicle. A head curtain extending downwardly from the frame structure and into the opening is also employed. As the vehicle backs into the shelter, the side and head curtains deflect in toward the dock under the influence of impact from and frictional engagement with the truck. A windstrap is often employed between the frame structure and the lateral ends of the head curtain. The purpose of such a windstrap is to prevent the head curtain from undue movement caused by wind, particularly movement that would, for example, cause the head curtain to flip up on top of the supporting structure and out of contact with a vehicle. The windstrap disposed between the frame structure and the ends of the head curtain basically prevents the head curtain from moving beyond a certain range. At the same time, the windstrap provides the necessary flexibility to allow the head curtain to move in response to the truck without placing undue stresses on the curtain. If, for example, the ends of the head curtain were attached directly to the frame structure, as opposed to being indirectly attached through the windstrap, the curtain would be stretched between such connections each time a vehicle backed into the shelter. This undue stress would be undesirable, thus suggesting the need for use of a windstrap.
Dock seals also use a windstrap. A dock seal may be generally distinguished from a dock shelter in that a dock seal typically has resilient foam pads as a supporting structure, as opposed to the rigid frame structure of conventional shelters. These resilient foam pads are disposed and intended to be impacted by the sidewalls of the backing vehicle, to compress the pads and thus form a tight seal between the sidewalls and the pads. In certain installations, it is advantageous to also have a head pad across the top of such a loading dock seal. Often, however, application issues will indicate that a head curtain as opposed to a head pad is desirable. Several dock seals manufactured and sold by Frommelt Products Corporation of Dubuque, IA use a head curtain in a dock seal. These products include Frommelt's TP-903 dock seal, its L-pad dock seal, and the ELIMINATOR.TM. dock seal, which combines both foam side members, as well as side curtains as seen in conventional dock shelters. Each of these products includes a windstrap connected to the head curtain for the same purpose as the windstrap described in regard to the dock shelters. In a dock shelter, however, the windstrap is connected to the rigid frame structure immediately behind the head curtain. In a dock seal, however, the only structure immediately behind the head curtain is the foam pad, which is not suitable for anchoring of a windstrap. Accordingly, windstraps on dock seals typically are connected to the head curtain, and are then anchored into a rigid structure, such as a wood backer disposed behind the side pad and adjacent the building wall. Thus, as seen in prior art FIGS. 1 and 2, the windstrap turns a corner from the front of the head curtain, and then extends along the side surface of the side pad before being secured at the rear of the side pad to the backerboard.
Such an arrangement of the windstrap can lead to undue wear of the windstrap. Each time a trailer backs against the head curtain, the windstrap is stretched. As a result, the windstrap rubs along the fabric in which the foam pad is encased, and also rubs along the corner of the foam pad. Over time, this friction between the windstrap and the pad base fabric can abraid the windstrap, leading to premature failure. This becomes not only a maintenance and cost issue, but also an issue of effectiveness of the seal. When a windstrap fails, the head curtain of the seal can be subject to undesirable blowing and billowing for windy conditions.